Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual page 239

8.
Set the redundant settings in the following items.
[Navigation window]  [Parameter]  [Module Information]  [RJ71EN71]  [Port 1 Module Parameter (Ethernet)] 
[Application Settings]  [Redundant System Settings]
9.
Set whether to issue a system switching request for the user connection.
[Navigation window]  [Parameter]  [Module Information]  [RJ71EN71]  [Port 1 Module Parameter (Ethernet)] 
[Application Settings]  [Redundant System Settings]  [System Switching Request Issue at Communication Error] 
[User Connection]
10.
In the "System A/B Setting" window, set the redundant function module of own system to system A, and either reset the
CPU modules of both systems or power off and on both systems.
[Online]  [Redundant PLC Operation]  [System A/B Setting]
1 FUNCTIONS
1.17 Redundant System Function
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